GHRP-6 vs IGF-1 LR3
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
GHRP-6
Growth Hormone Releasing Peptide 6 (GHRP-6) is one of the first synthetic growth hormone secretagogues discovered. It stimulates significant GH release but is known for causing intense hunger.
Full details →IGF-1 LR3
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified version of IGF-1 with extended half-life and enhanced potency. The modifications prevent binding to IGF binding proteins, increasing bioavailability.
Full details →Side-by-Side Comparison
| Aspect | GHRP-6 | IGF-1 LR3 |
|---|---|---|
| Dose Range | 100 mcg–300 mcg | 20 mcg–100 mcg |
| Frequency | 3x daily | 1x daily |
| Cycle Length | 8–12 weeks | 4–6 weeks |
| Route | subcutaneous | subcutaneous |
| Mechanism | Acts as a ghrelin mimetic, binding to the GHS-R receptor in the pituitary and hypothalamus. Stimulates GH release and also significantly increases appetite by mimicking ghrelin's hunger-signaling effects. | Binds to IGF-1 receptors to promote protein synthesis, muscle growth, and fat metabolism. The LR3 modification (13 amino acid extension and arginine substitution) extends half-life from minutes to 20-30 hours. |
| Typical Dosage | Typical dosing: 100-300mcg administered 2-3 times daily. Often combined with GHRH peptides like CJC-1295 for synergistic effects. | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. |
| Administration | Subcutaneous injection. Best administered on an empty stomach. The strong hunger response can be beneficial for those trying to gain weight but challenging for cutting. | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. |
| Side Effects | Intense hunger (most notable effect), water retention, increased cortisol and prolactin, tingling/numbness, and potential blood pressure changes. | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. |
| Best For |
What They Have in Common
GHRP-6, IGF-1 LR3 are both commonly used for:
Key Differences
Unique to IGF-1 LR3:
Which Has Stronger Evidence?
| Goal | GHRP-6 | IGF-1 LR3 |
|---|---|---|
| Muscle Growth | high | high |
| Recovery & Healing | medium | medium |
Key Studies
GHRP-6
- Growth hormone-releasing peptide 6 (GHRP-6) hydrogel for acute kidney injury therapy via metabolic regulation.
Journal of nanobiotechnology, 2025
- Growth hormone releasing peptide-6 (GHRP-6) prevents doxorubicin-induced myocardial and extra-myocardial damages by activating prosurvival mechanisms.
Frontiers in pharmacology, 2024
- [D-Lys3]-GHRP-6 exhibits pro-autophagic effects on skeletal muscle.
Molecular and cellular endocrinology, 2015
IGF-1 LR3
- IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep.
American journal of physiology. Endocrinology and metabolism, 2025
- Revolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration.
International journal of biological macromolecules, 2025
- Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets.
Journal of developmental origins of health and disease, 2023
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